Hojun-Cho
b401cced05
wwstage's $64 frame was 24B below required — the second struct-return's @retscr write at -88(BP) landed below SP. Silent miscompile masked by bootstrap-window luck. The fix retires the stomp by enforcing single-slot @retscr at emit-time. cstage was per-site-fresh (wasteful but safe, frame $96); aligned UP to single-slot for ABI consistency with wwstage's @-prefix convention, not for correctness. Both stages now produce $64 frame; second return reuses the first's -64..-48(BP) slot. Generalizes #38's c.tagscrsz SSoT pattern to c.retscroff (wwstage) and cg_retscr (cstage). Returns are terminal — only one fires per call, so the two slots' lifetimes never overlap; single-slot is structurally correct. wwstage's emit-side dedup was incomplete post-#27 (cgblock save/restore unwinds the @-prefix stub); the @retscr fast path in localadd bypasses the c.locals walk. Test 718: 4 rows × {cstage runtime, wwstage runtime, byte-id, stomp sentinel}. Stomp sentinel scans .s for any -N(BP) where N>64 and fails the row if found — catches below-SP writes that bootstrap byte-id would miss in a lucky window. Row 2 (3-return) byte-id disabled per task #15 (pre-existing label-counter skew, unrelated to #14). Polarity catalog this session: - #9 wwstage OVER (tagged-return slot) - #11 wwstage UNDER (struct-by-value param decompose) - #14 wwstage UNDER (struct multi-return @retscr — silent stomp)